for tlie Microscope. 51 



This is a handsome form of mould, with slender stem 

 much and equally branched, and bearing at the tips small 

 elliptical acrospores. (PI. V., fig. 26.) 



359. PARSNIP MOULD (Peronospora niuea). Occurs on 

 parsnip, wood angelica, and other umbelliferous plants. 

 The patches on the leaves are white, and very conspicuous. 

 The threads are produced in bundles, each thread being 

 short and once or twice forked, bearing subglobose 

 acrospores which have a blunt projection at the apex. 



360. DOCK MOULD (Peronospora obliqua). A curious 

 little dwarf species is very common on dock-leaves in 

 whitish patches. The threads are often simple, some- 

 times forked, and bear at the apex large elliptical acro- 

 spores, which are usually attached obliquely. 



361. SPINACH MOULD (Peronospora effiisa}. Thismould 

 occurs in dirty-looking patches on the leaves of spinach, 

 goosefoot, and other similar plants. The threads are in 

 bundles, short, thick, and from two to six times forked. 



362. NETTLE MOULD (Peronospora Urticcz). Common 

 on the leaves of nettles, in white patches, often of a cir- 

 cular form. The threads of the mould are small and 

 loosely, from four to six times, forked, with large acrospores. 



363. FASCICULATE MOULD (Polyactis fasciculata). 

 Not uncommon on old horse-chestnut husks and other 

 decaying vegetable substances. The threads are collected 

 in bundles, branched in the upper portion; the branches 

 terminated by clusters of spores. (PI. V., fig. 30.) 



364. GREY MOULD (Polyactis cinerea). Common on 

 old herbaceous stems, generally proceeding from a black 

 sclerotium. The threads are not collected in bundles, 

 but scattered, branched above, and bearing the clusters 

 of spores in a similar manner to the foregoing. 



365. GRASS OIDIUM (Oidiwn monilioides). Forming 

 dirty-white patches on grass leaves. These patches are 

 shown by one-inch power to consist of fascicles of deli- 

 cate threads, which the quarter inch demonstrates to con- 

 sist of rounded vesicles attached end to end in a beaded 

 manner. (PI. V., fig. n.) 



366. FRUIT OIDIUM (Outturn fructigenum}. Rotten 



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